#include <stdlib.h>
#include <stdio.h>

#include "defs.h"

typedef struct shorts
{
	struct shorts *next;
	short value;
} shorts;

int tokensetsize;
short *lookaheads;
short *LAruleno;
unsigned *LA;
short *accessing_symbol;
core **state_table;
shifts **shift_table;
reductions **reduction_table;
short *goto_map;
short *from_state;
short *to_state;

short **transpose(short **R, int n);
void traverse(int i);
void digraph(short **relation);

static int infinity;
static int maxrhs;
static int ngotos;
static unsigned *F;
static short **includes;
static shorts **lookback;
static short **R;
static short *INDEX;
static short *VERTICES;
static int top;

void set_state_table(void)
{
	register core *sp;

	state_table = NEW2(nstates, core *);
	for (sp = first_state; sp; sp = sp->next)
		state_table[sp->number] = sp;
}


void set_accessing_symbol(void)
{
	register core *sp;

	accessing_symbol = NEW2(nstates, short);
	for (sp = first_state; sp; sp = sp->next)
		accessing_symbol[sp->number] = sp->accessing_symbol;
}


void set_shift_table(void)
{
	register shifts *sp;

	shift_table = NEW2(nstates, shifts *);
	for (sp = first_shift; sp; sp = sp->next)
		shift_table[sp->number] = sp;
}


void set_reduction_table(void)
{
	register reductions *rp;

	reduction_table = NEW2(nstates, reductions *);
	for (rp = first_reduction; rp; rp = rp->next)
		reduction_table[rp->number] = rp;
}


void set_maxrhs(void)
{
	register short *itemp;
	register short *item_end;
	register int length;
	register int max;

	length = 0;
	max = 0;
	item_end = ritem + nitems;
	for (itemp = ritem; itemp < item_end; itemp++)
	{
		if (*itemp >= 0)
		{
			length++;
		} else
		{
			if (length > max)
				max = length;
			length = 0;
		}
	}

	maxrhs = max;
}


void initialize_LA(void)
{
	register int i, j, k;
	register reductions *rp;

	lookaheads = NEW2(nstates + 1, short);

	k = 0;
	for (i = 0; i < nstates; i++)
	{
		lookaheads[i] = k;
		rp = reduction_table[i];
		if (rp)
			k += rp->nreds;
	}
	lookaheads[nstates] = k;

	LA = NEW2(k * tokensetsize, unsigned);
	LAruleno = NEW2(k, short);
	lookback = NEW2(k, shorts *);

	k = 0;
	for (i = 0; i < nstates; i++)
	{
		rp = reduction_table[i];
		if (rp)
		{
			for (j = 0; j < rp->nreds; j++)
			{
				LAruleno[k] = rp->rules[j];
				k++;
			}
		}
	}
}

void set_goto_map(void)
{
	register shifts *sp;
	register int i;
	register int symbol;
	register int k;
	register short *temp_map;
	register int state2;
	register int state1;

	goto_map = NEW2(nvars + 1, short) - ntokens;
	temp_map = NEW2(nvars + 1, short) - ntokens;

	ngotos = 0;
	for (sp = first_shift; sp; sp = sp->next)
	{
		for (i = sp->nshifts - 1; i >= 0; i--)
		{
			symbol = accessing_symbol[sp->shift[i]];

			if (ISTOKEN(symbol))
				break;

			if (ngotos == MAXSHORT)
				fatal("too many gotos");

			ngotos++;
			goto_map[symbol]++;
		}
	}

	k = 0;
	for (i = ntokens; i < nsyms; i++)
	{
		temp_map[i] = k;
		k += goto_map[i];
	}

	for (i = ntokens; i < nsyms; i++)
		goto_map[i] = temp_map[i];

	goto_map[nsyms] = ngotos;
	temp_map[nsyms] = ngotos;

	from_state = NEW2(ngotos, short);
	to_state = NEW2(ngotos, short);

	for (sp = first_shift; sp; sp = sp->next)
	{
		state1 = sp->number;
		for (i = sp->nshifts - 1; i >= 0; i--)
		{
			state2 = sp->shift[i];
			symbol = accessing_symbol[state2];

			if (ISTOKEN(symbol))
				break;

			k = temp_map[symbol]++;
			from_state[k] = state1;
			to_state[k] = state2;
		}
	}

	FREE(temp_map + ntokens);
}



/*  Map_goto maps a state/symbol pair into its numeric representation.	*/

int map_goto(int state, int symbol)
{
	register int high;
	register int low;
	register int middle;
	register int s;

	low = goto_map[symbol];
	high = goto_map[symbol + 1];

	for (;;)
	{
		assert(low <= high);
		middle = (low + high) >> 1;
		s = from_state[middle];
		if (s == state)
			return (middle);
		else if (s < state)
			low = middle + 1;
		else
			high = middle - 1;
	}
}


void initialize_F(void)
{
	register int i;
	register int j;
	register int k;
	register shifts *sp;
	register short *edge;
	register unsigned *rowp;
	register short *rp;
	register short **reads;
	register int nedges;
	register int stateno;
	register int symbol;
	register int nwords;

	nwords = ngotos * tokensetsize;
	F = NEW2(nwords, unsigned);

	reads = NEW2(ngotos, short *);
	edge = NEW2(ngotos + 1, short);
	nedges = 0;

	rowp = F;
	for (i = 0; i < ngotos; i++)
	{
		stateno = to_state[i];
		sp = shift_table[stateno];

		if (sp)
		{
			k = sp->nshifts;

			for (j = 0; j < k; j++)
			{
				symbol = accessing_symbol[sp->shift[j]];
				if (ISVAR(symbol))
					break;
				SETBIT(rowp, symbol);
			}

			for (; j < k; j++)
			{
				symbol = accessing_symbol[sp->shift[j]];
				if (nullable[symbol])
					edge[nedges++] = map_goto(stateno, symbol);
			}

			if (nedges)
			{
				reads[i] = rp = NEW2(nedges + 1, short);

				for (j = 0; j < nedges; j++)
					rp[j] = edge[j];

				rp[nedges] = -1;
				nedges = 0;
			}
		}

		rowp += tokensetsize;
	}

	SETBIT(F, 0);
	digraph(reads);

	for (i = 0; i < ngotos; i++)
	{
		if (reads[i])
			FREE(reads[i]);
	}

	FREE(reads);
	FREE(edge);
}

void add_lookback_edge(int stateno, int ruleno, int gotono)
{
	register int i, k;
	register int found;
	register shorts *sp;

	i = lookaheads[stateno];
	k = lookaheads[stateno + 1];
	found = 0;
	while (!found && i < k)
	{
		if (LAruleno[i] == ruleno)
			found = 1;
		else
			++i;
	}
	assert(found);

	sp = NEW(shorts);
	sp->next = lookback[i];
	sp->value = gotono;
	lookback[i] = sp;
}

void build_relations(void)
{
	register int i;
	register int j;
	register int k;
	register short *rulep;
	register short *rp;
	register shifts *sp;
	register int length;
	register int nedges;
	register int done;
	register int state1;
	register int stateno;
	register int symbol1;
	register int symbol2;
	register short *shortp;
	register short *edge;
	register short *states;
	register short **new_includes;

	includes = NEW2(ngotos, short *);
	edge = NEW2(ngotos + 1, short);
	states = NEW2(maxrhs + 1, short);

	for (i = 0; i < ngotos; i++)
	{
		nedges = 0;
		state1 = from_state[i];
		symbol1 = accessing_symbol[to_state[i]];

		for (rulep = derives[symbol1]; *rulep >= 0; rulep++)
		{
			length = 1;
			states[0] = state1;
			stateno = state1;

			for (rp = ritem + rrhs[*rulep]; *rp >= 0; rp++)
			{
				symbol2 = *rp;
				sp = shift_table[stateno];
				k = sp->nshifts;

				for (j = 0; j < k; j++)
				{
					stateno = sp->shift[j];
					if (accessing_symbol[stateno] == symbol2)
						break;
				}

				states[length++] = stateno;
			}

			add_lookback_edge(stateno, *rulep, i);

			length--;
			done = 0;
			while (!done)
			{
				done = 1;
				rp--;
				if (ISVAR(*rp))
				{
					stateno = states[--length];
					edge[nedges++] = map_goto(stateno, *rp);
					if (nullable[*rp] && length > 0)
						done = 0;
				}
			}
		}

		if (nedges)
		{
			includes[i] = shortp = NEW2(nedges + 1, short);
			for (j = 0; j < nedges; j++)
				shortp[j] = edge[j];
			shortp[nedges] = -1;
		}
	}

	new_includes = transpose(includes, ngotos);

	for (i = 0; i < ngotos; i++)
		if (includes[i])
			FREE(includes[i]);

	FREE(includes);

	includes = new_includes;

	FREE(edge);
	FREE(states);
}

short **transpose(short **R, int n)
{
	register short **new_R;
	register short **temp_R;
	register short *nedges;
	register short *sp;
	register int i;
	register int k;

	nedges = NEW2(n, short);

	for (i = 0; i < n; i++)
	{
		sp = R[i];
		if (sp)
		{
			while (*sp >= 0)
				nedges[*sp++]++;
		}
	}

	new_R = NEW2(n, short *);
	temp_R = NEW2(n, short *);

	for (i = 0; i < n; i++)
	{
		k = nedges[i];
		if (k > 0)
		{
			sp = NEW2(k + 1, short);
			new_R[i] = sp;
			temp_R[i] = sp;
			sp[k] = -1;
		}
	}

	FREE(nedges);

	for (i = 0; i < n; i++)
	{
		sp = R[i];
		if (sp)
		{
			while (*sp >= 0)
				*temp_R[*sp++]++ = i;
		}
	}

	FREE(temp_R);

	return (new_R);
}


void compute_FOLLOWS(void)
{
	digraph(includes);
}

void compute_lookaheads(void)
{
	register int i, n;
	register unsigned *fp1, *fp2, *fp3;
	register shorts *sp, *next;
	register unsigned *rowp;

	rowp = LA;
	n = lookaheads[nstates];
	for (i = 0; i < n; i++)
	{
		fp3 = rowp + tokensetsize;
		for (sp = lookback[i]; sp; sp = sp->next)
		{
			fp1 = rowp;
			fp2 = F + tokensetsize * sp->value;
			while (fp1 < fp3)
				*fp1++ |= *fp2++;
		}
		rowp = fp3;
	}

	for (i = 0; i < n; i++)
		for (sp = lookback[i]; sp; sp = next)
		{
			next = sp->next;
			FREE(sp);
		}

	FREE(lookback);
	FREE(F);
}

void digraph(short **relation)
{
	register int i;

	infinity = ngotos + 2;
	INDEX = NEW2(ngotos + 1, short);
	VERTICES = NEW2(ngotos + 1, short);
	top = 0;

	R = relation;

	for (i = 0; i < ngotos; i++)
		INDEX[i] = 0;

	for (i = 0; i < ngotos; i++)
	{
		if (INDEX[i] == 0 && R[i])
			traverse(i);
	}

	FREE(INDEX);
	FREE(VERTICES);
}


void traverse(int i)
{
	register unsigned *fp1;
	register unsigned *fp2;
	register unsigned *fp3;
	register int j;
	register short *rp;

	int height;
	unsigned *base;

	VERTICES[++top] = i;
	INDEX[i] = height = top;

	base = F + i * tokensetsize;
	fp3 = base + tokensetsize;

	rp = R[i];
	if (rp)
	{
		while ((j = *rp++) >= 0)
		{
			if (INDEX[j] == 0)
				traverse(j);

			if (INDEX[i] > INDEX[j])
				INDEX[i] = INDEX[j];

			fp1 = base;
			fp2 = F + j * tokensetsize;

			while (fp1 < fp3)
				*fp1++ |= *fp2++;
		}
	}

	if (INDEX[i] == height)
	{
		for (;;)
		{
			j = VERTICES[top--];
			INDEX[j] = infinity;

			if (i == j)
				break;

			fp1 = base;
			fp2 = F + j * tokensetsize;

			while (fp1 < fp3)
				*fp2++ = *fp1++;
		}
	}
}

void lalr(void)
{
	tokensetsize = WORDSIZE(ntokens);

	set_state_table();
	set_accessing_symbol();
	set_shift_table();
	set_reduction_table();
	set_maxrhs();
	initialize_LA();
	set_goto_map();
	initialize_F();
	build_relations();
	compute_FOLLOWS();
	compute_lookaheads();
}
